Abstract: The invention relates to a sensor for a terahertz imaging system which can be integrally produced using a semiconductor technology, comprising a flat substrate (60) made from semiconductor material that is transparent to terahertz radiation, configured to be oriented parallel to an object (12) to be analyzed; and a plurality of terahertz radiation receivers arranged according to a matrix (10) in the substrate. The sensor is lensless and comprises at least one terahertz radiation transmitter arranged in the substrate, so that the radiation emitted by the transmitter is reflected on the object (12) to be analyzed, towards the receivers.

Abstract: A radar system is provided that includes a receive channel including a complex baseband and a processor coupled to the receive channel to receive a first plurality of digital intermediate frequency (IF) samples from an in-band (I) channel of the complex baseband and a corresponding second plurality of digital IF samples from a quadrature (Q) channel of the complex baseband, wherein the processor is configured to execute instructions to compute at least one failure metric based on the first plurality of digital IF samples and the second plurality of digital IF samples.

Abstract: A system for safe transmission of an RF electromagnetic power beam to a receiver for conversion into electric power. The receiver has an antenna array for receiving the RF beam and electrical circuitry to receive a corresponding RF electrical current from the antenna array. The circuitry includes a converter for generating DC current from the RF electrical current, and includes at least one component that reflects part of the RF current back towards the antenna array. This converts the reflected portion of the RF electrical current into a retransmitted RF electromagnetic beam having the same frequency as the RF electromagnetic power beam, and is directed back towards the transmitter. The receiver monitors the reflected RF current, and transmits a proportional signal back to a controller. The controller reduces the transmitted power beam if its interference with the retransmitted beam would generate a field intensity above a safe level.

Abstract: Examples disclosed herein relate to a dual edge-fed Slotted Waveguide Antenna (SWA). The SWA has a plurality of antenna sections having a plurality of radiating slots and configured to radiate one or more transmission signals through the plurality of radiating slots, in which the plurality of antenna sections are symmetric about a termination region between the plurality of antenna sections. The SWA also has a plurality of distributed feed networks coupled to the plurality of antenna sections and configured to serve as a feed to the plurality of antenna sections, in which each of the plurality of distributed feed networks is a corporate feed structure comprising a plurality of transmission lines and further configured to propagate the one or more transmission signals through the plurality of transmission lines. Other examples disclosed herein relate to a radar system for use in an autonomous driving vehicle.

Abstract: A method of forming a mixed mode response from a single ended mode input includes modeling a first voltage controlled current source based on relative values of a vpositive input signal and a vnegative input signal and modeling a second voltage controlled current source based on relative values of the vpositive input signal and the vnegative input signal. A method of forming a single ended mode response from a mixed mode input modeling a first voltage controlled current source based on relative values of a vDIFFin input signal and a vCOMMin input signal and modeling a second voltage controlled current source based on relative values of the vDIFFin input signal and the vCOMMin input signal, the second voltage controlled being connected to ground through a second terminating impedance that is equal to the reference impedance (Z0).

Abstract: Provided is a navigation signal transmitter capable of ensuring reduction in frequency deviation of a terrestrially transmitted navigation signal at low cost. The navigation signal transmitter is operable to receive a transmission wave, generate a synchronization pulse in synchronization with a predetermined data frame, generate an internal clock fundamental oscillation by a reference signal synchronizing section (550) using the synchronization pulse as a reference signal, generate an IMES signal based on the internal clock fundamental oscillation, and transmit the IMES signal. The reference signal synchronizing section (550) comprises a counter circuit (551), a comparator (553), a low-pass control filter (554), a D/A converter (555) and a voltage controlled oscillator (556).

Abstract: A disturbance signal removing device is provided. The device includes an antenna for transmitting a modulated pulse signal and a non-modulated pulse signal, and a transmission frequency setter for selectively setting as a transmission frequency band of the modulated pulse signal any one of a plurality of mutually different frequency bands of the modulated pulse signal that are different from a transmission frequency band set to the non-modulated pulse signal. The transmission frequency setter switches between the plurality of transmission frequency bands of the modulated pulse signal.

Abstract: A method for determining the filling level of a product in a tank using electromagnetic signals, comprising: a) generating a transmission signal having a predetermined length; b) propagating the signal towards the product; c) receiving a reflected signal; d) determining whether the received signal overlaps the transmitted signal in the time-domain; e) setting an overlap-parameter to 1 if overlap is detected, otherwise setting the overlap-parameter to 0; if the state of the overlap parameter is not changed and if no overlap is detected, generate a signal having a length exceeding the previous length and repeat step b); and if the state of the overlap-parameter is not changed and if an overlap is detected, generate a signal having a length shorter than the previous length and repeat step b); and if the state of the overlap-parameter is changed, determine the filling level based on the length of the transmitted signal.

Abstract: A radar system including a switching mode power converter. A pulse radar unit is configured to transmit RF pulses with a pulse repetition frequency. The power converter includes a switching controller that is configured to control at least one switching element. The switching controller is configured to receive a frequency modulated input signal. The modulation frequency of the input signal is configured to be derived from the pulse repetition frequency of the radar unit.

Abstract: Systems and methods for allowing dual-mode radar operation. An exemplary transmission system includes a hybrid coupler that receives a signal produced by a synthesizer and couples the received signal to two output ports. A pulse transmitter receives a pulse transmit-activate signal from a controller, receives an input signal from the hybrid coupler and, if the activate signal has been received, amplifies the received signal based on a predefined desired pulse output transmission setting. A frequency-modulation continuous-wave (FMCW) transmitter receives an FMCW transmit-activate signal from the controller, receives an input signal from the hybrid coupler and, if the activate signal has been received, amplifies the received input signal based on a predefined desired FMCW output transmission setting. An isolator protects the pulse transmitter during FMCW operation and also the FMCW transmitter from receiving power reflected off of pulse transmitter components.

Abstract: A method is provided. A first edge on a first gating signal is generated, and a local oscillator and a shared clocking circuit with the first edge on the first gating signal. A second edge on a second gating signal is generated following the first edge on the first gating signal, and a receiver circuit is activated with the second edge on the second gating signal, where the receiver circuit includes a mixer. A transmit pulse following the first edge on the first gating signal is generated with the transmit pulse having a third edge. A switch that short circuits outputs of the mixer is then released following the later of the third edge of the transmit pulse and a delay.

Abstract: An RF pulse signal generation switching circuit for controlling an output of a power FET for amplifying a high frequency signal to generate an RF pulse signal that is the high frequency signal pulse formed into a pulse-wave shape is provided. The circuit includes first and third n-type FETs of which gates are inputted with a control pulse that supplies a rise timing and a fall timing of a pulse, and a second n-type FET of which a gate is connected with a drain of the first FET. A source of the first FET and a source of the third FET are grounded, respectively. The drain of the first FET is applied with a first drive voltage via a resistor. A drain of the second FET is applied with a second drive voltage. A source of the second FET is connected with a drain of the third FET and the connection point therebetween is connected with the power FET. A capacitor is connected between the connection point and an end of the resistor from which the first drive voltage is applied.

Abstract: Optical range finders are configured to transmit optical bursts toward a target and detect a corresponding received burst. DC offset in the received burst due to square law detection can be offset based on a difference between high pass and low pass filtered portions of the received burst. Edge records associated with bursts can be obtained, and correlated with a reference signal or waveform to obtain a range estimate.

Abstract: A guided wave radar transmitter for interface measurement comprises a probe defining a transmission line for sensing level of two immiscible liquids to define an interface therebetween. A pulse circuit generates pulses on the transmission line and receives a reflected signal from the transmission line. The reflected signal selectively includes a level pulse representing material level and an interface pulse representing interface level. A controller operates in an interface mode to determine the material level and the interface level responsive to receiving the level pulse and the interface pulse. The controller operates in a medium identification mode responsive to not receiving the interface pulse, comprising calculating an estimated amplitude of the level pulse for the two immiscible liquids and comparing actual amplitude of the level pulse to the estimated amplitude of the level pulse to identify the medium in the vessel.

Abstract: A presence detector unit (PDU) of the type relying on microwave radiation provides a signal indicating movement within a defined space when such movement occurs. A source of microwave radiation within a housing projects a beam of microwave radiation directed through a side of the housing to suffuse at least a portion of the defined space. A detector within the housing senses changes in microwave radiation reflected back toward the detector. An adjustable beam occlusion structure is supported by the housing and blocks a portion of the microwave radiation emanating from the source and through the side of the housing.

Abstract: A radar system includes an antenna. The radar system comprises a processor for providing an error in ground speed estimate based upon Doppler velocity data, and a transmitter. The frequency of radar signals from the transmitter is adjusted according to a velocity of the aircraft calculated using the error in ground speed estimate or using the error in ground speed estimate. The adjusted frequency can allow ground clutter to be removed by high pass filtering in one embodiment.

Abstract: A system and method for pseudo real time collection of receive signal data in a single- or multi-channel ground penetrating radar. Each channel transmits electromagnetic impulses into a medium under test during each of a plurality of runs over the medium. Run receive signals are received in response to the transmitted impulses. Each run receive signal is sampled multiple times at a run sample rate. The sample points of each run are delayed by delay sequences with respect to the sample points of the other runs. The sample points of the individual runs are stored as a composite set of sample points representative of a receive signal sampled at an effective sample rate equal to a multiple of the run sample rate where the multiple is the number of runs.

Abstract: A Luneburg lens is used in conjunction with a patch antenna array. The patch antenna array is conformed or adapted to cover a portion or backside of the Luneburg len's surface with the backplane of the conformed antenna array defining a field of regard (FOR) in which objects are detected and tracked. A processor is connected to a receiver/exciter module which connects to transmit/receive modules which are connected to the individual patch antennas through a network of MEMS switches. In a receive mode, selected subarrays of the conformed patch antenna array are scanned during selected time intervals with the sum and delta beams being formed coherently in amplitude and phase to realize amplitude monopulse sensing and angle tracking of an object.

Abstract: An iterative method for modifying an initial time signal to form a created signal having a prescribed envelope, and frequency notches at prescribed frequency values, wherein the created signal closely resembles the initial time signal, the envelope of the created time signal is the prescribed envelope, and the Fourier magnitude of the created time signal at the prescribed frequency values is nearly zero. The created time signal may be a real-valued signal as well as a complex-valued time signal which closely resembles an arbitrary initial time signal, including initial time signals which are standard transmit signals for radar systems, and which have Fourier transform magnitudes with notches and stop-bands at prescribed frequency values. These notches and stop bands are created by enforcing nulls of prescribed order at the prescribed frequency values within the modified time signal.

Abstract: A radar sensor for motor vehicles, having a transmitting part, which has two oscillators and a 90° phase shifter for generating a transmission signal, a first comparison signal, and a second comparison signal, which is phase shifted by 90° with respect to the first comparison signal, and a receiving part having an I mixer for mixing a received signal with the first comparison signal and a Q mixer for mixing the received signal with the second comparison signal, in which the transmitting part has a first transmit mixer, whose inputs are directly connected to the two oscillators, and a second transmit mixer, whose one input is directly connected to a first of the two oscillators and whose other input is connected via the phase shifter to the other oscillator.

Abstract: An on-vehicle wireless communication apparatus for transmitting transmission data having positional information wirelessly at a frequency includes: a receiver receiving the transmission data from another apparatus; a positional information acquiring unit acquiring the positional information; a location specifying unit specifying a location relationship between a vehicle and another vehicle based on the positional information of the vehicle and the another vehicle; an another-apparatus transmission timing specifying unit specifying a transmission timing of the another apparatus when the another vehicle is located immediately in front of the vehicle; and a transmission timing adjusting unit adjusting a transmission timing of the apparatus so that the transmission data is transmitted at the frequency with an adjusted transmission timing, which is later by a predetermined time than the transmission timing of the another apparatus.

Abstract: A method for the detection of sensitivity losses of an FMCW radar locating device due to diffuse sources of loss, in which the radar locating device emits a transmit signal whose frequency is periodically modulated in successive modulation ramps, and at least one power characteristic of at least one frequency portion of a signal received by the radar locating device is evaluated, wherein the power of the transmit signal is varied cyclically, in each case after the completion of a modulation ramp, and the sensitivity losses are determined on the basis of differences in the power characteristics of signals received during successive modulation ramps having identical modulation.

Abstract: Traffic awareness systems and methods include receiving data regarding a first aircraft and determining the location of the first aircraft relative to the location of a second aircraft. An indication of the first aircraft may be provided to a display based on a determination that the relative location of the first aircraft is within a field of view associated with the display.

Abstract: A method and apparatus for providing power management for a device including a radar unit and an ad hoc network node are presented. The present invention involves various individual components of the device being turned on and off in various sequences in order to minimize power draw of the device. This involves starting individual components ahead of when they are required so they are fully functional when needed.

Abstract: In radio communication between a central unit in an airborne vehicle and a radio communication terminal, the central unit controls a setting of transmission power depending on the altitude of the airborne vehicle during climbing and descending flight using hysteresis.

Abstract: An electromagnetic transmitter arrangement includes an antenna line array or subarray defining at least first and second ends, and including first, second, third, fourth, and fifth antenna elements, arranged with the first antenna element at the first end, the fifth element at the second end, the third element at the center, the second element between the first and third elements, and the fourth element between the third and fifth elements. Multiple (N) corresponding radio frequency sources are provided, each source communicating with a respective antenna element along a given radio-frequency signal path extending from the given signal source to the given antenna element, and where a first signal source generates signals at frequency f0, and each of the N?1 additional sources generate signals at frequencies of f0±(N?1)?f, where N is an integer greater than or equal to 5.

Abstract: A communication processing apparatus alternately transmits a carrier wave carrying a command and receives a response from a tag while transmitting an unmodulated carrier wave. A transmission control unit changes the phase of the unmodulated carrier wave transmitted from a transmission/reception circuit in response to start of reception of the reflected wave from the tag. The transmission/reception circuit includes a circuit for separating and detecting an I signal and a Q signal included in the reflected wave from the tag. A phase detection unit uses the I signal and the Q signal to detect change of the phase of the reflected wave. A distance calculation unit measures a time from a change of the phase of the unmodulated carrier wave to a detection of a corresponding change in the phase of the reflected wave, and uses the time to calculate the distance from the antenna to the tag.

Abstract: Present novel and non-trivial optical, laser-based measuring systems and method are disclosed. An optical, laser-based, or LIDAR measuring apparatus is comprised of a radiation receiver/transmitter, a beam-forming optical element, a beam steering device comprised of a deviation optical element and at least one actuator used to steer the deviation optical element in response to drive signal(s) from a processor.

Abstract: A microwave imaging system uses microwave radiation provided by a microwave source to image targets. The system includes an array of antenna elements that are capable of being programmed with a respective direction coefficient to direct the microwave illumination from the microwave source toward a position on the target. The antenna elements are further capable of being programmed to receive reflected microwave illumination reflected from the position on the target. A processor is operable to measure an intensity of the reflected microwave illumination to determine a value of a pixel within an image of the target. Multiple beams can be directed towards the target to obtain corresponding pixel values for use by the processor in constructing the image.

Abstract: An apparatus includes a stable local oscillator, which includes a first control loop. The first control loop includes a first voltage-controlled oscillator configured to generate a first output signal and a first phase-locked loop. The apparatus also includes a frequency up-converter configured to increase a frequency of the first output signal. The apparatus further includes a second control loop configured to receive the up-converted first output signal. The second control loop includes a second voltage-controlled oscillator configured to generate a second output signal and a second phase-locked loop. The second control loop may further include a mixer having a first input coupled to the frequency up-converter, a second input coupled to the second voltage-controlled oscillator, and an output coupled to the second phase-locked loop. A reference frequency source may be configured to generate a signal identifying a reference frequency and to provide that signal to the phase-locked loops.

Abstract: A radar system includes at least one transmit array comprising a plurality of metamaterial elements. The radar system further includes at least one near-field stimulator for inputting electromagnetic signal to the transmit array so that a sub-wavelength target is illuminated with an electromagnetic wave.

Abstract: A method of operating a multi-function phased array radar system having an antenna array populated with dual-pol antenna elements is described. The method includes selectively controlling individual dipoles of each dual-pol antenna element in order to operate the array in either a polarimetric mode with improved cross-pol isolation, or in a multi-mission mode, wherein a plurality of singularly-polarized signals are produced.

Abstract: A monostatic multi-beam radar sensor includes a group antenna and a mixer system made up of a plurality of transfer mixers connected to antenna elements of the group antenna. A first number of the transfer mixers is switched to isolation mode and a second number of the transfer mixers is switched to transfer mode in order to realize different directional characteristics for the transmit and receive operation.

Abstract: An antenna configuration is described for high frequency (HF) or very high frequency (VHF) radars contained in a single vertical post. The radar may include a vertical dipole or monopole transmitting antenna collocated with a three-element receive antenna. The three antennas including two crossed loops and a vertical element are used in a direction-finding (DF) mode. Isolation between the three antennas produces high quality patterns useful for determining target bearings in DF mode. The single vertical post is sufficiently rigid mechanically that it may be installed along a coast without guy wires.

Abstract: The present disclosure describes a method of aligning a forward looking radar module mounted to a vehicle. The forward looking radar module includes a radar, a tilt sensor, attached to the radar module, and a tilt sensor output. The method uses the tilt sensor output to check the radar's alignment with the vehicle's horizontal thrust direction.

Abstract: A monostatic multibeam radar sensor device for a motor vehicle, including a directional characteristic of an antenna unit having at least one transceiving channel and at least one receiving channel, and including a mixer system, which has an at least approximately isolating mixer for at least one of the receiving channels. The at least approximately isolating mixer includes a Gilbert cell mixer, which, due to a non-ideal isolation between an input of the local oscillator signal and the corresponding receiving channel, emits a transmission power via this receiving channel, using an overcoupling signal, the transmission power influencing the directional characteristic of the antenna unit and the directional characteristic being switchable by controlling the phase position of the overcoupling signal.

Abstract: A radar system is disclosed for forming a scanning receive beam from signals received by a phased array having a plurality of sub arrays. An exemplary radar system includes a plurality of phase units each configured to receive a signal from one or more sub arrays. Each phase unit includes a waveform generator configured to generate an analog waveform having a frequency corresponding to a time-varying phase shift. Each waveform generator is arranged to digitally generate the analog waveform, and output a comparison of the received signal with the waveform, incorporating the time-varying phase shift. The system further includes a combining unit configured to combine the outputs from the plurality of phase units to form a scanning receive beam.

Abstract: An ultra-wideband (UWB) dual impulse transmitter is made up of a trigger edge selection circuit actuated by a single trigger input pulse; a first step recovery diode (SRD) based pulser connected to the trigger edge selection circuit to generate a first impulse output; and a second step recovery diode (SRD) based pulser connected to the trigger edge selection circuit in parallel to the first pulser to generate a second impulse output having a selected delay from the first impulse output.

Abstract: An observation signal processing apparatus transmits a pulse signal as a search signal, generates an observation value based on a reflected signal against a target and a delay modulation pulse signal, and performs coherent integration on the observation value to output an integration value. The apparatus includes a section for determining a coherent integration count, a section for transmitting pulse signals equivalent to the coherent integration count, a section for calculating a phase correction amount based on an estimated relative speed, and a section for performing phase-weighted coherent integration on observation values for the number of times equivalent to the coherent integration count based on the phase correction amount.

Abstract: A radar device includes: a frequency modulating unit for modulating a frequency of a transmission signal by a triangular wave; a transmitting unit for pulsing the frequency modulated transmission signal to transmit the pulsed transmission signal as a transmission pulse; a receiving unit for generating a beat signal based on a frequency difference between a frequency modulated transmission signal and a reflected received pulse; a range gate setting unit for setting a range gate that determines a sampling timing of the received pulse based on a transmitting timing of the transmission pulse; a sampling unit for sampling the beat signal in each of range gates; a distance and relative velocity calculating unit for calculating a distance to a target and a relative velocity based on the sampled beat signal; and a control unit for controlling a transmission pulse width and a range gate width depending on a subject vehicle velocity.

Abstract: A method examining an object using millimeter-wave signals includes: (a) providing at least two millimeter-wave signal sources; (b) transmitting at least two millimeter-wave signals having at least two different frequencies from the signal sources illuminate the object; (c) in no particular order: (1) determining whether a return reflected signal is above a threshold level; [a] if yes, processing the return signal to identify object shape; [b] if not, processing another return signal; and (2) determining whether a return intermodulation product or harmonic signal is detected; [a] if yes, processing the return signal to identify object nature; [b] if not, processing another return signal; (d) determining whether checked all return signals; (1) if not, processing another return signal; (2) if yes, proceeding to step (e); (e) determining whether results are satisfactory; (1) if not, changing frequency of at least one of the wave signals; (2) if yes, terminating the method.

Abstract: A method and apparatus for detecting objects located underground. In one advantageous embodiment, a detection system detects objects having electrical non-linear characteristics located underground. The detection system comprises a transmitter unit, a receiver, and a processor. The transmitter transmits a plurality of pulsed radio frequency signals having a first frequency and a second frequency into a ground. The receiver monitors for a response radio frequency signal having a frequency equal to a difference between the first frequency and a second frequency, wherein the response radio frequency signal is generated by an object having the non-linear conductive characteristics in response to receiving the plurality of electromagnetic signals. The processor is connected to the transmitter unit and the receiver, wherein the processor controls an operation of the transmitter unit and the receiver, wherein the object is detected when the response radio frequency signal is detected by the receiver.

Abstract: This disclosure is related to a magnetron including a cylindrical cathode having a center axis, an anode coaxially arranged with the cathode so as to be separated from the cathode via a predetermined space, and a pair of pole pieces provided to both ends of the cathode in the axial direction so as to oppose to each other and having opposing faces perpendicular to the axial direction. The pole piece has a first ridge of a ring shape that is formed on the opposing face and is coaxial with the cathode.

Abstract: A microwave/millimeter wave sensor apparatus including a planar radiation type oscillator substrate having an inner-layer GND interposed between a front surface side dielectric substrate and a rear surface side dielectric substrate and a pair of conductor patches in an axis-symmetric manner on the side of the front surface layer. A gate and drain of a microwave transistor are respectively connected to the conductor patches to supply power to the gate and the drain of the microwave transistor through a gate-side RF choke circuit and a drain-side RF choke circuit. An impedance line satisfying an oscillation condition is connected to a source and a transmit RF signal in an RF zone as a planar radiation type oscillator is transmitted and a receive RF signal as reflected waves is received from a measured object, thus obtaining an IF signal as the sensing information through homodyne mixing.

Abstract: Disclosed is an apparatus for measuring sizes of a human body, such as the length of an arm, the size of a waist and the width of a shoulder, in the state that a person does not take off its clothes, using millimeter waves. The apparatus includes a plurality of millimeter-wave transmission/reception units, a rotation unit and a digital signal processing unit. The plurality of millimeter-wave transmission/reception units are arranged in a circular shape around an object to be measured, transmit a millimeter wave to the object to be measured, and receive a signal reflected or scattered by the object to be measured. The rotation unit rotates a circular structure in which the plurality of millimeter-wave transmission/reception units are arranged. The digital signal processing unit analyzes the object to be measured using size and phase information of the signal received by the plurality of millimeter-wave transmission/reception units.

Abstract: A ground penetrating radar system is described that is able to create both low frequency, wide pulses, and high frequency, narrow pulses, to enable both deep and shallow operation of the ground penetrating radar on demand, including simultaneous operation.

Abstract: A method for estimating the distance between a transmitter and at least one receiver. The transmitter has radio transmission circuitry, at least part of which is operable in a first operation mode for transmitting a first signal type within a first bandwidth and in a second operation mode for transmitting a second signal type including at least a ranging component which occupies a second bandwidth which encompasses and exceeds the first bandwidth. The method includes the steps of: (i) operating part of the radio transmission circuitry in a second operation mode, (ii) transmitting a signal of a second signal type, (iii) receiving a signal on one receiver and (iv) estimating the distance between the transmitter and a receiver from the ranging component in each received signal. A suitable transmitter and receiver for implementing the method are described.

Abstract: Embodiments of a target tracking system and method with jitter reduction suitable for directed energy systems are generally described herein. In some embodiments, the directed energy system includes a target tracking system to track one or more track points on a moving target, and a beam transmission unit to maintain a directed energy beam on a selected one of the track points in response to tracking control signals provided by the target tracking system. The track points may be smaller than a spot size of the directed energy beam maintained on the target.

Abstract: The present invention is intended to realize a transmitter whose internal signal processing function can be duplicated without having to add any hardware components. The transmitter converts an input signal into an output signal using a plurality of calculation steps, comprising a backward calculation means for executing the plurality of calculation steps in reverse direction.

Abstract: For use in conjunction with a microwave antenna having a radiator array configured to scan in a horizontal direction, a method for scanning in the vertical direction. A first FMCW microwave signal having a first bandwidth is transmitted at a first microwave frequency and the echo, if any, is received by the radiator array. A second FMCW microwave signal having a second bandwidth is also transmitted at a different center frequency and the echo, if any, is received by the radiator array. The different frequencies cause an elevational shift in the received signal. The receipt of the echoes is then processed to identify the location or locations of the object or objects causing the echo and communicating such location or locations to a user.